Enhanced Immunoadsorption on Imprinted Polymeric Microstructures with Nanoengineered Surface Topography for Lateral...

Lateral flow immunoassay devices have revolutionized the style of on-site disease detection and point-of-care testing in the past few decades. The surface nanotopography of a solid substrate is a dominant parameter in the efficiency of antibody immobilization, but precise control over surface roughness has not been fully investigated. Here we presented lateral flow immunoassay platforms with nanometer-scale surface roughness, reproducibly engineered using thermal nanoimprinting lithography, and investigated the effects of surface nanotopography on immunoadsorption and immunoassay performance. We fabricated three types of imprinted polycarbonate sheets with microcone array structures having different degrees of surface roughness using three types of molds fabricated by micromachining or laser ablation. The structures fabricated by laser-ablated nickel mold exhibited numerous bumps measuring several tens of nanometers, which enhanced antibody adsorption. We performed sandwich immunoassays of C-reactive protein in serum samples and achieved highly sensitive detection with a detection limit of ∼0.01 μg mL^-1 and a broad dynamic range. The present results provide useful information on the remarkable effect of nanoengineered surfaces on biomolecule adsorption, and the platforms presented here will widen the applicability and versatility of lateral flow immunoassay devices.